1. Field of the Invention
The present invention relates to a wireless communication system using a Mobile Internet Protocol (MIP). More particularly, the present invention relates to a system and a method for processing an MIP session setup at a Foreign Agent (FA) of a wireless communication system.
2. Description of the Related Art
A wireless communication system using a Foreign agent Care-of-Address (FaCoA) Mobile Internet Protocol (MIP) service performs an MIP session setup procedure in order to register a Mobile Node (MN). For example, a wireless communication system performs an MIP session setup procedure as illustrated in FIG. 1 in order to register a client MIP node.
FIG. 1 illustrates a session setup procedure of a client MIP node in a conventional wireless communication system.
As illustrated in FIG. 1, in the case where an MN 100 accesses a Foreign Agent (FA) 110, the MN 100 transmits a Mobile Internet Protocol (MIP) registration request message to the FA 110 in step 131.
When the MIP registration request message is received, the FA 110 generates a hash table for a Network Access Identifier (NAI) of the MN 100 in step 133. For example, the FA 110 assigns a session IDentification (ID) to the NAI of the MN 100. In addition, the FA 110 generates a hash key of the MN 100 by performing a hash algorithm on the NAI of the MN 100. At this point, the FA 110 generates the hash table by assigning the session ID assigned to the NAI to the hash key of the MN 100.
The FA 110 transmits an MIP registration request message to a Home Agent (HA) 120 in order to register the MN 100 in step 135. When a plurality of MNs transmit MIP registration request messages in step 131, the FA 110 transmits an MIP registration request message of each MN to the HA 120.
When an MIP registration request message is received from the FA 110, the HA 120 generates a binding cache for the MN 100 in step 137. In the case where the binding cache for the MN 100 has been already generated, the HA 120 updates the binding cache for the MN 100.
The HA 120 transmits an MIP registration reply message informing registration information of the MN 100 to the FA 110 in step 139.
When the MIP registration reply message is received from the HA 120, the FA 110 searches for an NAI included in the MIP registration reply message from the hash table, and determines an MN corresponding to the MIP registration reply message in step 141. For example, the FA 110 generates a hash key by performing a hash algorithm on the NAI included in the MIP registration reply message. The FA 110 determines a session ID assigned to the generated hash key from the hash table, and determines an MN corresponding to the NAI assigned the determined session ID.
When the MN 100 is determined by searching for the NAI from the hash table, the FA 110 transmits the MIP registration reply message to the MN 100 in order to inform that the MN 100 has been properly registered in the HA 120 in step 143.
For another example, the wireless communication system performs an MIP session setup procedure as illustrated in FIG. 2 in order to register a proxy MIP node.
FIG. 2 illustrates a session setup procedure of the proxy MIP node in a conventional wireless communication system.
In the case where an MN 200 accesses an FA 210, the MN 200 transmits a Dynamic Host Configuration Protocol (DHCP) discover message to the FA 210 in order to request an Internet Protocol (IP) address in step 231.
When the DHCP discover message is received from the MN 200, the FA 210 generates a hash table for an NAI of the MN 200 in step 233. For example, the FA 210 assigns a session ID to the NAI of the MN 200. In addition, the FA 210 generates a hash key of the MN 200 by performing a hash algorithm on the NAI of the MN 200. At this point, the FA 210 generates the hash table by assigning the session ID assigned to the NAI to the hash key of the MN 200. Here, the FA 210 determines the NAI of the MN 200 from an Authentication Authorization and Accounting (AAA) server.
The FA 210 transmits an MIP registration request message to an HA 220 in order to register the MN 200 in step 235. When a plurality of MNs transmit MIP registration request messages, the FA 210 transmits an MIP registration request message of each MN to the HA 220.
When an MIP registration request message is received from the FA 210, the HA 220 generates a binding cache for the MN 200 in step 237. In the case where the binding cache for the MN 200 has already been generated, the HA 220 updates the binding cache for the MN 200.
The HA 220 transmits an MIP registration reply message informing of registration information of the MN 200 to the FA 210 in step 239.
When the MIP registration reply message is received from the HA 220, the FA 210 searches for an NAI included in the MIP registration reply message from the hash table, and determines an MN corresponding to the MIP registration reply message in step 241. For example, the FA 210 generates a hash key by performing a hash algorithm on the NAI included in the MIP registration reply message. The FA 210 determines a session ID assigned to the generated hash key from the hash table, and determines an MN corresponding to the NAI assigned the determined session ID.
When the MN 200 is determined through searching for the NAI from the hash table, the FA 210 includes an IP address assigned to the MN 200 in a DHCP offer message and transmits the DHCP offer message to the MN 200 in step 243.
When the DHCP offer message is received, the MN 200 determines the IP address assigned by the FA 210 from the DHCP offer message. The MN 200 transmits a DHCP request message to the FA 210 in order to confirm the assigned IP address in step 245.
When the DHCP request message is received, the FA 210 transmits a DHCP ACKnowledgment (ACK) message to the MN 200 in response to the DHCP request message in step 247.
As described above, the FA of the wireless communication system which uses an MIP determines an MN corresponding to an NAI included in a MIP registration reply message provided from the HA by searching for the NAI from the hash table.
In this case, a delay occurs for the FA to generate the hash table using the hash algorithm or a search for a session ID included in the hash table. Furthermore, in the case where a plurality of session IDs are assigned to one hash key, a longer delay occurs for the FA to search for an NAI from the hash table.
In addition, the FA stores a hash table in order to maintain mapping information regarding NAIs of MNs requesting registration and corresponding session IDs.